Occupational asthma

Should be suspected in all adult patients with asthma.

An occupational history should be taken to identify work-related causes. Details of work exposures should be obtained from material safety data sheets and other material available to the patient from their workplace.

Objective evidence of asthma should be obtained from spirometry, a bronchodilator response, and/or a methacholine challenge. Tests should be performed when the patient is symptomatic and/or within days of having exposure to a suspected etiologic agent.

If sensitizer-induced occupational asthma is suspected, additional testing of asthma should be done, preferably while the patient is still working. Whenever possible an immunologic response to a suspected work sensitizer should be demonstrated by skin or in vitro tests.

Where possible, an early diagnosis based on as much objective data as is available should be made.

In sensitizer-induced occupational asthma, removal from any further exposure to that agent should be recommended.

In irritant-induced occupational asthma, preventive measures should be implemented in the workplace to reduce future exposures and episodes.

For all causes of occupational asthma, the clinician should continue treating the asthma as appropriate, assist in the initiation of any appropriate compensation claim, and consider other workers at risk.

Occupational asthma (OA) is asthma caused by the workplace and may result from immunologic or nonimmunologic stimuli.[1]Tarlo SM, Liss GM. Occupational asthma: an approach to diagnosis and management. CMAJ. 2003;168:867-871. http://www.cmaj.ca/cgi/content/full/168/7/867 http://www.ncbi.nlm.nih.gov/pubmed/12668547?tool=bestpractice.com There are 2 main forms. Sensitizer-induced OA is caused by immunologic stimuli and develops after a latency period between first exposure and the onset of symptoms.[2]Tarlo SM, Lemiere C. Occupational asthma. N Engl J Med. 2014;370:640-649. http://www.ncbi.nlm.nih.gov/pubmed/24521110?tool=bestpractice.com [3]Malo JL, Vandenplas O. Definitions and classification of work-related asthma. Immunol Allergy Clin North Am. 2011;31:645-662. http://www.ncbi.nlm.nih.gov/pubmed/21978849?tool=bestpractice.com Irritant-induced OA (including reactive airways dysfunction syndrome) is caused by nonimmunologic stimuli.[4]Vandenplas O, Wiszniewska M, Raulf M, et al. EAACI position paper: irritant-induced asthma. Allergy. 2014;69:1141-1153. http://onlinelibrary.wiley.com/doi/10.1111/all.12448/full http://www.ncbi.nlm.nih.gov/pubmed/24854136?tool=bestpractice.com